<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    
  </head>
  <body>
    <div id="app">
        <ol>
            <li v-for="(item,index) in title" @mouseenter="getChange(index)" @mouseleave="cleanChange">{{item.item}}</li>
        </ol>
        <div class="box">{{content}}</div>
    </div>
    
  </body>
</html>